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Author Kappler, J.P.; Besnus, M. J.; Beaurepaire, E.; Meyer, A.; Sereni, J.; Nieva, G.
Title Magnetic transition in the CePd3Bx system Type Journal Article
Year 1985 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal JMMM
Volume 47 Issue Pages 111-114
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Abstract Susceptibility, high-field magnetisation, resistivity and heat capacity data for the CePd3Bx system are reported. The observed valence transition of Ce is the first example of a transition from an IV state system to a stable magnetic 4f1 state system, whose properties are tentatively ascribed to an aleatory cooperative state, due to the inhomogeneous character of the valence transition, rather than to a Kondo effect.
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Call Number BT @ gnieva @ Serial 422
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Author Pureur, P.; Fraga, G. L.; Brandao, D. E.; Caudron,R.; Safa, H.; Nieva, G.
Title Specific heat measurements in scandium-rare earth anisotropic spin glasses Type Journal Article
Year 1987 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal J. Magn. Magn. Mater.
Volume 68 Issue 2 Pages 213-217
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Abstract We report on specific heat measurements at low temperature of the anisotropic spin glass alloys ScDy 3 at%, ScEr 4.25 at% and ScEr 10 at%. We find that at the lowest temperature range the data indicate the occurrence of an anisotropy induced gap around zero frequency in the density of states of the magnetic excitations. Moreover, some of our specific heat curves present a maximum coinciding with Tg, raising thus the question of thermal signs for a spin glass phase transition in anisotropic systems.
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Call Number BT @ gnieva @ Serial 425
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Author Antonio, D.; Dolz, M.I.; Pastoriza, H.
Title Magnetization measurement of single La0.67Ca0.33MnO3 nanotubes in perpendicular magnetic fields using a micromechanical torsional oscillator Type Journal Article
Year 2010 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal
Volume 322 Issue 5 Pages 488-493
Keywords Manganite nanotubes; Micromachined magnetometers; Shape anisotropy
Abstract Using a silicon micromechanical resonator as a sensitive magnetometer, the authors have studied both experimentally and theoretically the magnetic behavior of two isolated ferromagnetic nanotubes of perovskite La0.67Ca0.33MnO3. The article investigates the specific configuration where a magnetic field H is applied perpendicular to the magnetic easy axis of an isolated nanotube characterized by an uniaxial anisotropy constant K. In this situation, the magnetization M reduces the effective elastic constant kM of the resonator. This softening of the mechanical system is opposed to the hardening effect of M observed in a previous work, where H was applied parallel to the easy axis. Moreover, in this magnetic field configuration two distinct magnetization regimes are manifested, depending on the magnitude of H. For H[not double greater-than sign]2K/M the magnetization is almost parallel to the applied magnetic field and for H[double less-than sign]2K/M it is almost parallel to the easy axis of the nanotube. At a certain value of H there is a sharp transition
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Call Number BT @ hernan @ 13272 Serial 585
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Author Sirena, M.; Haberkorn, N.; Granada, M.; Steren, L.B.; Guimpel, J.
Title Oxygen and disorder effect in the magnetic properties of manganite films Type Journal Article
Year 2004 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal Proceedings of the International Conference on Magnetism (ICM 2003)
Volume 272-276, Part 2 Issue Pages 1171-1173
Keywords Manganite fims; Oxigenation; Magnetic properties
Abstract We have made a systematic study of the magnetic properties of low doped manganite films submitted to different oxygenation treatments. We have found that oxygenation dynamics depends critically of the strain field in the sample. The TC and the Mr increase as the oxygen content is increased. A decrease of the coercive field of the LSMO-STO films was observed, indicating that annealing treatments increase the oxygen content reducing oxygen vacancies.
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Call Number BT @ jguimpel @ Serial 622
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Author Franco, D.G.; Carbonio, R.E.; Kaul, E.E.; Nieva, G.
Title Tailoring the ground state of the ferrimagnet La2Ni(Ni1/3Sb2/3)O6 Type Journal Article
Year 2013 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal J. Magn. Magn. Mater.
Volume 346 Issue Pages 196-202
Keywords Ferrimagnetic; Double perovskite; Magnetic frustration; Superexchange and super-superexchange interaction; Magnetic oxide
Abstract We report on the magnetic and structural properties of La2Ni(Ni1/3Sb2/3)O6 in polycrystal, single crystal and thin film samples. We found that this material is a ferrimagnet ( T c ≈ 100 K ) which possesses a very distinctive and uncommon feature in its virgin curve of the hysteresis loops. We observe that bellow 20 K it lies outside the hysteresis cycle, and this feature was found to be an indication of a microscopically irreversible process possibly involving the interplay of competing antiferromagnetic interactions that hinder the initial movement of domain walls. This initial magnetic state is overcome by applying a temperature dependent characteristic field. Above this field, an isothermal magnetic demagnetization of the samples yield a ground state different from the initial thermally demagnetized one.
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Call Number BT @ pedrazp @ Serial 666
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Author Betancourth, D.; Facio, J.I.; Pedrazzini, P.; Jesus, C.B.R.; Pagliuso, P.G.; Vildosola, V.; Cornaglia, P.S.; García, D. J.; Correa, V. F.
Title Low Temperature magnetic properties of GdCoIn5 Type Journal Article
Year 2015 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal J. Magn. Magn. Mater.
Volume 374 Issue Pages 744-747
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Abstract A comprehensive experimental and theoretical study of the low temperature properties of GdCoIn5 was performed. Specific heat, thermal expansion, magnetization and electrical resistivity were measured in good quality single crystals down to 4He temperatures. All the experiments show a second-order-like phase transition at 30 K probably associated with the onset of antiferromagnetic order. The magnetic susceptibility shows a pronounced anisotropy below T N with an easy magnetic axis perpendicular to the crystallographic ĉ-axis. Total energy GGA+U calculations indicate a ground state with magnetic moments localized at the Gd ions and allowed a determination of the Gd-Gd magnetic interactions. Band structure calculations of the electron and phonon contributions to the specific heat together with Quantum Monte Carlo calculations of the magnetic contributions show a very good agreement with the experimental data. Comparison between experiment and calculations suggests a significant anharmonic contribution to the specific heat at high temperature (View the MathML sourceT≳100K).
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Call Number BT @ victor.correa @ Serial 701
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Author Facio, J.I.; Betancourth, D.; Cejas Bolecek, N.R.; Jorge, G.A.; Pedrazzini, P.; Correa, V.F.; Cornaglia, P.S.; Vildosola, V.; García D.J.
Title Lattice specific heat for the RMIn5 (R=Gd, La,Y; M=Co, Rh) compounds: Non-magnetic contribution subtraction Type Journal Article
Year 2016 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal J. Magn. Magn. Mater.
Volume 407 Issue Pages 406-4011
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Call Number BT @ victor.correa @ Serial 730
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Author Carreras Oropesa, W.G.; Encina, S.; Pedrazzini, P.; Correa, V.F.; Sereni, J.G.; Vildosola, V.; García D.J.; Cornaglia, P.S.
Title Minimal model for the magnetic phase diagram of CeTi1-xScxGe, GdFe1-xCoxSi, and related materials Type Journal Article
Year 2020 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal
Volume 503 Issue Pages 166614
Keywords Magnetism; RTX
Abstract We present a theoretical analysis of the magnetic phase diagram of CeTi1-xScxGe and GdFe1-xCoxSi as a function

of the temperature and the Sc and Co concentration x, respectively. CeScGe and GdCoSi, as many other RTX

(R=rare earth, T=transition metal, X=p-block element) compounds, present a tetragonal crystal structure

where bilayers of R are separated by layers of T and X. While GdFeSi and CeTi0.75Sc0.25Ge are ferromagnetic,

CeScGe and GdCoSi order antiferromagnetically with the R 4f magnetic moments on the same bilayer aligned

ferromagnetically and magnetic moments in nearest neighbouring bilayers aligned antiferromagnetically. The

antiferromagnetic transition temperature TN decreases with decreasing concentration x in both compounds and

for low enough values of x the compounds show a ferromagnetic behavior. Based on these observations we

construct a simplified model Hamiltonian that we solve numerically for the specific heat and the magnetization.

We find a good qualitative agreement between the model and the experimental data. Our results show that the

main magnetic effect of the Sc→Ti and Co→Fe substitution in these compounds is consistent with a change in

the sign of the exchange coupling between magnetic moments in neighbouring bilayers. We expect a similar

phenomenology for other magnetic RTX compounds with the same type of crystal structure.
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Call Number BT @ victor.correa @ Serial 856
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Author Steren, L.B.; Sirena, M.; Guimpel, J.
Title Substrate influence on the magnetoresistance and magnetic order in La0.6Sr0.4MnO3 films Type Journal Article
Year 2000 Publication JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Abbreviated Journal
Volume 211 Issue 1-3 Pages 28-34
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Abstract We report structural, magnetic and transport measurements on La0.6Sr0.4MnO3 thin films grown on MgO and TiSrO3 substrates with thickness varying from 5 to 500 nm. We find that the lattice mismatch between substrates and films affects the morphology and induced-strains of the films. We show that these two different effects strongly influence the ferromagnetic order, the metal-insulator transition, the localization of the current carriers and the magnetoresistance of these materials. (C) 2000 Elsevier Science B.V. All rights reserved.
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Notes (up) ISI:000085772100006 Approved no
Call Number BT @ hernan @ Serial 179
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Author Pedrazzini, P.; Berisso, M.G.; Sereni, J.G.; Trovarelli, O.; Geibel, C.
Title Magnetic phase diagram of Ce(CuxRh1-x)(2) Si-2 Type Journal Article
Year 2001 Publication JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Abbreviated Journal
Volume 226 Issue Pages 161-163
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Abstract Magnetic, thermal and transport measurements on Ce(CuxRh1-x)(2)Si-2 are presented, The obtained phase diagram shows a rapid decrease of the magnetic order on the Rh rich-side. as determined by magnetic susceptibility measurements, followed by a region without magnetic order for x > 0.2. In this region, the electronic specific heat coefficient increases moderately up to 0.2J/mol K-2 for x = 0.8. evaluated at 0.5 K. Around 5 K a small anomaly is observed in the 0.8. As a function of doping, a maximum develops below 10 K in the electrical resistance. specific heat for 0.4 less than or equal to x less than or equal to 0.8. As a function of doping, a maximum develops below 10 K in the electru=ical resistance. Particularly, at x = 0.8, the temperature of the maximum of the electrical resistance slope coincides with the anomaly observed in the specific heat. (C) 2001 Elsevier Science B.V. All rights reserved.
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Notes (up) ISI:000170708600054 Approved no
Call Number BT @ hernan @ Serial 297
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